Functional and clinical evidence for NDRG2 as a candidate suppressor of liver cancer metastasis

We searched for potential suppressors of tumor metastasis by identifying the genes that are frequently down-regulated in hepatocellular carcinomas (HCC) while being negatively correlated with clinical parameters relevant to tumor metastasis, and we report here on the identification of N-myc downstream regulated gene 2 (NDRG2) as a promising candidate. NDRG2 expression was significantly reduced in HCC compared with nontumor or normal liver tissues [87.5% (35 of 40) and 62% (62 of 100) at RNA and protein levels, respectively]. Reduction of NDRG2 expression was intimately associated with promoter hypermethylation because its promoter region was found to carry extensively methylated CpG sites in HCC cell lines and primary tumors. Immunohistochemical analysis of NDRG2 protein in 100 HCC patient tissues indicated that NDRG2 expression loss is significantly correlated with aggressive tumor behaviors such as late tumor-node-metastasis (TNM) stage (P = 0.012), differentiation grade (P = 0.024), portal vein thrombi (P = 0.011), infiltrative growth pattern (P = 0.015), nodal/distant metastasis (P = 0.027), and recurrent tumor (P = 0.021), as well as shorter patient survival rates. Ectopically expressed NDRG2 suppressed invasion and migration of a highly invasive cell line, SK-Hep-1, and experimental tumor metastasis in vivo, whereas small interfering RNA-mediated knockdown resulted in increased invasion and migration of a weakly invasive cell line, PLC/PRF/5. In addition, NDRG2 could antagonize transforming growth factor beta1-mediated tumor cell invasion by specifically down-regulating the expression of matrix metalloproteinase 2 and laminin 332 pathway components, with concomitant suppression of Rho GTPase activity. These results suggest that NDRG2 can inhibit extracellular matrix-based, Rho-driven tumor cell invasion and migration and thereby play important roles in suppressing tumor metastasis in HCC.     

BDNF表达下调抑制HepG2细胞侵袭的相关分子机制研究

目的：应用特异性siRNA下调HepG2细胞中BDNF表达,观察对细胞凋亡和侵袭的影响并探讨相关分子机制。方法：在人HCC细胞系HepG2中,采用Western blot方法检测BDNF的表达,采用ELISA方法检测培养液上清BDNF的分泌水平。特异性BDNF-siRNA转染细胞,采用FITC-phalloidin染色方法检测actin细胞骨架的变化,采用Western blot方法检测细胞内RhoA、Rac1、Cdc42的活化情况。同时,流式细胞术检测细胞凋亡,Transwell小室测定细胞侵袭能力的变化。结果：HepG2细胞培养上清中BDNF含量为88.56±7.45 pg/ml。在HepG2细胞中,特异性BDNF-siRNA显著抑制BDNF的表达,干扰细胞内actin细胞骨架聚合,RhoA或Rac1活性受到抑制,同时凋亡细胞数增加、细胞侵袭能力下降。结论：干扰BDNF的表达可以显著抑制细胞侵袭能力,这可能与阻断actin细胞骨架聚合、以及RhoA或Rac1活化相关。BDNF/TrkB信号通路可能作为阻断HCC发展演进的新靶点,有待于进一步深入研究。     

The iron chelator Dp44mT inhibits hepatocellular carcinoma metastasis via N-Myc downstream-regulated gene 2 (NDRG2)/gp130/STAT3 pathway

Here we showed that hepatocellular carcinoma (HCC) cell lines with high metastatic potential had low levels of NDRG2. The iron chelator Dp44mT up-regulated NDRG2, suppressed epithelial-mesenchymal transition (EMT) and inhibited tumor metastasis in HCC having high metastatic potential. Also Dp44mT attenuated the TGF-β1-induced EMT in HCC having low metastatic potential. In agreement, silencing endogenous NDRG2 with shNDRG2 in HCC cells attenuated the effect of Dp44mT. We showed that the NDRG2/gp130/STAT3 pathway can mediate Dp44mT effects. In agreement, we found that a combination of NDRG2 expression and p-STAT3 levels is a strong predictor of prognosis in HCC patients. We suggest that up-regulation of NDRG2 by Dp44mT is a promising therapeutic approach in HCC.     

下调UHRF1的表达在抑制肝癌进展中的作用

目的 探讨UHRF1的异常表达在肝癌（hepatocellular carcinoma, HCC）进展中的作用机制。方法 采用RT-PCR和Western blot法检测UHRF1在20例HCC标本中的mRNA和蛋白表达水平, Western blot法检测不同转移潜能的肝癌细胞HepG2、SMMC7721、MHCC97L和HCCLM3中的UHRF1 的表达水平;siRNA技术干扰HCCLM3细胞中UHRF1表达后,MTT法检测细胞增殖,Western blot 法检测BAX和BCL-2表达水平的改变,流式细胞术检测HCCLM3细胞周期和细胞凋亡的变化。结 果 UHRF1在肺癌组织中的表达水平较癌旁组织显著上调（P<0.05）,随着肝癌细胞转移潜能升高而UHRF1表达水平也依次升高（P<0.01）;siRNA技术干扰HCCLM3细胞中UHRF1表达后,HCCLM3细胞生长速度明显下降（P＜0.05）,HCCLM3细胞的促凋亡蛋白BAX表达水平明显上升,而抑凋亡蛋白BCL-2表达水平明显下降;UHRF1-siRNA干扰HCCLM3细胞48 h时,细胞周期分布无明显影响（P＞0.05）;但UHRF1表达下调有促凋亡作用,与对照组相比,干扰组的细胞凋亡率显著升高,差异有统计学意义（P＜0.05）。结论 UHRF1基因在肝癌组织中表达上调,下调UHRF1的表达能够抑制肝癌进展,可能是通过诱导肿瘤细胞凋亡来实现的。     

Small interfering RNA-directed targeting of RON alters invasive and oncogenic phenotypes of human hepatocellular carcinoma cells

The recepteur d'origine nantais (RON) receptor tyrosine kinase is highly expressed in various cancers including human hepatocellular carcinoma (HCC) and involved in tumor progression. The aims of the current study were to evaluate whether RON affects tumor cell behavior and oncogenic signaling cascades in HCC cells. We investigated the biologic role of RON on tumor cell behavior and oncogenic signaling cascades including Akt, c-Raf and extracellular signal-regulated kinase (ERK) by using the small interfering RNA (siRNA) in HCC cell lines, chang, HepG2 and Huh7. Knockdown of RON suppressed tumor cell migration and invasion in all tested HCC cell lines. The proportion of apoptotic cells induced by knockdown of RON was greater than that induced by transfection of the scramble siRNA in all tested HCC cell lines. Knockdown of RON resulted in cell cycle arrest in the G2/M phase of chang and Huh7 cells, and sub G1 phase of HepG2 cells. Knockdown of RON activated cleaved caspase-3 and PARP, and down-regulated the expression of Bcl-2, Bcl-xL and survivin, leading to induction of apoptosis in all tested cell lines. Knockdown of RON negatively regulates the progression of the cell cycle by decreasing cyclin D1 and D3, and increasing p21 and p27 in all tested cell lines. The phosphorylation of Akt, c-Raf and ERK1/2 signal proteins was significantly blocked by knockdown of RON in all tested cell lines. These results suggest that RON is associated with invasive and oncogenic phenotypes such as tumor cell migration, invasion, resistance to apoptosis and cell cycle arrest through the modulation of Akt, c-Raf and ERK signaling cascades in HCC cells.     

Suppression of MMP-9 activity by NDRG2 expression inhibits clear cell renal cell carcinoma invasion

Members of the NDRG (N-Myc downstream-regulated) gene family have been shown to play a variety of roles in human malignancies. Recently, it was shown decreased expression in clear cell renal cell carcinoma (CCRCC) and inhibited cell proliferation, but the role of the NDRG2 in CCRCC invasion has not been described. We examined the expression of NDRG2 protein in CCRCC samples and the association between NDRG2 expression and CCRCC patients survival. Real-time RT-PCR and immunohistochemical analysis were used to measure NDRG2 expression in 60 paired CCRCC and adjacent normal tissues. Changes in cell invasion were detected by up- or down-regulating NDRG2 by adenovirus or siRNA. We found that NDRG2 expression is significantly down-regulated in CCRCC at mRNA and protein levels in a manner negatively associated with aggressive tumor behaviors, such as TNM stage (P?=?0.003), Fuhrman??s grade (P?=?0.024), tumor invasion (P?=?0.001) and tumor recurrence (P?=?0.004), as well as shorter patient survival rates (P?=?0.0041). Furthermore, NDRG2 could suppress CCRCC cell invasion through regulating MMP-9 expression and activity. So, these results suggest that NDRG2 can inhibit extracellular matrix-based tumor cell invasion and thereby play important roles in suppressing tumor metastasis in CCRCC. NDRG2 expression may also be a significant prognostic indicator for CCRCC.     

NDRG1 as a biomarker for metastasis,recurrence and of poor prognosis in hepatocellular carcinoma

N-myc downstream-regulated gene 1 (NDRG1) has been reported to be a multifunctional protein associated with carcinogenesis, however, the cellular function of NDRG1 remains elusive in human cancers. Here, our proteomics profile analysis of HCC tissues with different metastatic capabilities revealed that NDRG1 was correlated with metastasis and recurrence in HCC patients after liver transplantation (LT). Immunohistochemical staining of 143 HCC patients after LT showed that NDRG1-positive expression had poor prognosis, either for shorter disease-free survival or overall survival (P < 0.001), compared with NDRG1-negative expression. Multivariate analysis confirmed NDRG1 as an independent prognostic value (P < 0.001). In addition, in vitro experiments HCC cells with small interfering RNA against NDRG1 significantly suppressed its proliferation, colony formation, invasion and migration ability. Microarray analysis revealed that NDRG1 modulated the expression of genes associated with transmembrane transporter activity, chemoattractant activity, immune response, cell adhesion and cell proliferation process. Taken together, these results suggested that NDRG1 was an important molecule in controlling HCC metastasis and thus suggested as a novel biomarker for predicting HCC recurrence after LT.     

FEN1过表达对肝细胞癌细胞生物学行为及患者预后的作用

目的 探讨FEN1在肝细胞癌中的表达及其在肝细胞癌发生发展中的作用。方法 应用RTqPCR及免疫组织化学方法检测FEN1基因在52例肝细胞癌组织及相应癌旁组织中的表达。FEN1基因特异性siRNA转染肝癌细胞株HepG2并用Western blot检测转染效率。用MTT及流式细胞技术检测干扰FEN1后HepG2增殖及凋亡情况。Transwell实验检测HepG2迁移、侵袭能力改变。结果 RT-qPCR结果显示与癌旁正常组织相比较,FEN1高表达于肝细胞癌组织（P<0.01）。免疫组织化学与临床资料统计分析进一步证实FEN1的高表达与肿瘤分化程度（P=0.017）、肝内转移（P=0.046）、临床TNM分期（P=0.020）相关,而与患者性别、年龄、术前AFP值及肿瘤直径无相关性（P>0.05）。通过siRNA干扰肝癌细胞株HepG2中FEN1基因表达,MTT及流式细胞术检测表明干扰FEN1表达后肝癌细胞株HepG2增殖受到明显抑制（P<0.05）,凋亡率明显增加（P<0.05）。Transwell实验发现干扰FEN1后可明显抑制HepG2迁移、侵袭能力（P<0.05）。结论 FEN1在肝细胞癌组织中高表达,高FEN1表达提示肿瘤分化程度低,易转移及预后差,干扰FEN1后抑制肝癌细胞增殖,诱导其凋亡,并降低肝癌细胞体外迁移和侵袭能力。FEN1基因可成为肝细胞癌诊断及治疗的一个新生物靶点。     

NTS/IL-8通路对肝细胞肝癌侵袭迁移和EMT的影响

  目的  探讨神经降压素（neurotensin,NTS）对肝细胞肝癌（hepatocellular carcinoma,HCC）细胞合成和分泌白细胞介素8（interleukin-8,IL-8）的影响及NTS/IL-8通路活化对HCC侵袭、迁移和上皮间质转化（epithelial-mesenchymal transition,EMT）的作用。  方法  通过慢病毒基因转染构建神经降压素受体1（neurotensin receptor1,NTR1）高表达的HCC细胞系Hep3BNTR1hi,利用小干扰RNA构建NTR1低表达HCC细胞系HepG2NTR1-。通过实时荧光定量PCR（RT-qPCR）和酶联免疫吸附（ELISA）实验检测外源性NTS刺激前后HCC细胞IL-8分泌量的变化;利用划痕修复实验和Transwell实验观察阻断IL-8受体后HCC细胞侵袭迁移能力的变化;采用Western blot比较阻断IL-8受体后HCC细胞EMT相关蛋白的表达变化。  结果  外源性NTS刺激和高表达NTR1可促进Hep3B和HepG2细胞合成和分泌IL-8（P均 < 0.01）,阻断或降低NTR1表达后IL-8的表达显著降低（P < 0.05,P < 0.01）。外源性NTS刺激和高表达NTR1可提高HCC细胞的侵袭和迁移能力（P均 < 0.05）,阻断IL-8受体,即阻断NTS/IL-8信号下传,HCC细胞的划痕修复率和侵袭细胞数均降低（P均 < 0.001）,同时伴有E-cadherin表达增加,N-cadherin、β-catenin表达降低。  结论  外源性NTS刺激和高表达NTR1可以刺激HCC细胞合成和分泌IL-8,阻断NTS/IL-8信号下传会降低肝癌细胞EMT和侵袭迁移能力。      

TPX2 knockdown suppressed hepatocellular carcinoma cell invasion via inactivating AKT signaling and inhibiting MMP2 and MMP9 expression

Objective： Targeting protein for Xenopus kinesin-like protein 2 （TPX2） is a nuclear proliferation-related protein that plays a critical role in the formation of mitotic spindle. High expression of TPX2 has been observed in several types of tumors. However, the role of TPX2 in hepatocellular carcinoma （HCC） remains unclear. Our study aimed to investigate the effect of TPX2 on HCC cell invasion. Methods： The immortalized normal human liver cell line L02 and six HCC cell lines including SMMC- 7721, BEL-7402, Huh-7, HepG2, Hep3B and SKHepl were subjected to qRT-PCR and western blot for TPX2 mRNA and protein, respectively. Furthermore, TPX2 small interfering RNA （siRNA） was used to knock down TPX2 expression in SMMC-7721 and HepG2 cells. Cell proliferation and invasion were determined by MTT and transwell assays. Otherwise, expression of p-AKT, MMP2 and MMP9 were evaluated by western blot in SMMC-7721 cells. Results： The expression of TPX2 in HCC cell lines was markedly higher than that in normal human liver cell line. TPX2 knockdown using a specific TPX2-siP, NA reduced the number of invaded cells and inhibited cell proliferation in SMMC-7721 and HepG2 cells. Furthermore, TPX2 knockdown resulted in inactivation of AKT signaling and down-regulation of MMP2 and MMP9 expression in SMMC-7721 cells. Conclusions： Our study identified that TPX2 might contribute to tumor cell invasion through activating AKT signaling and subsequently increasing MMP2 and MMP9 in HCC.     

Caveolin-1 is related to invasion,survival, and poor prognosis in hepatocellular cancer

Caveolin-1 is the principal components of caveolae membranes, implicated in oncogenesis and angiogenesis. Until now, its expression and functional significance in hepatocellular carcinoma (HCC) are still unclear. In the present study, we demonstrated that expression of caveolin-1 was markedly upregulated in HCC patients. In addition, increased caveolin-1 expression correlated positively with the histological differentiation, portal venous invasion, hepatic venous invasion, intrahepatic metastases, and recurrence, suggesting a role for caveolin-1 in the progression of HCC. HepG2 cell line was transfected with pcDNA3.1/caveolin-1 to observe the significance of the change in caveolin-1 expression. We showed that caveolin-1 overexpression could not only protect HepG2 cells from apoptosis but also enhance its migration and invasion by upregulating MMP-2, MMP-9, and VEGF expressions. Collectively, our clinical and in vitro data indicate that the status of caveolin-1 expression may be one of causative factors for the invasion and poor prognosis in HCC.     

More expressions of BDNF and TrkB in multiple hepatocellular carcinoma and anti-BDNF or K252a induced apoptosis,supressed invasion of HepG2 and HCCLM3 cells

Background

Brain-derived neurotrophic factor (BDNF) and its receptor Tropomysin-related kinase B (TrkB) are commonly up-regulated in a variety of human tumors. However, the roles of BDNF/TrkB in hepatocellular carcinoma (HCC) have been poorly investigated.

Methods

We evaluated the expressions of BDNF and TrkB in 65 cases of HCC by immunohistochemical staining. Moreover, in human HCC cell lines of HepG2 and high metastatic HCCLM3, the secretory BDNF in supernatant was measured by ELISA, the effects of BDNF neutralizing antibody or Trk tyrosine kinase inhibitor K252a on apoptosis and invasion were examined by flow cytometry and transwell assay respectively.

Results

Higher expression of BDNF (63.1%) or positive expression of TrkB (55.4%) was found in HCC specimens, which was significantly correlated with multiple and advanced stage of HCC. BDNF secretory level in HCCLM3 was higher than that in HepG2 cells. Both anti-BDNF and K252a effectively induced apoptosis and suppressed invasion of HepG2 and HCCLM3 cells.

Conclusions

These findings suggested that BDNF/TrkB are essential for HCC cells survival and invasion. BDNF/TrkB signaling should probably be an effective target to prevent HCC advancement.     

Overexpression of HOXA1 correlates with poor prognosis in patients with hepatocellular carcinoma

HOXA1 overexpression is sufficient for malignant transformation of nontumorigenic epithelial cells. It is known that HOXA1, which was upregulated in squamous cell carcinomas, affects both cell growth and death. The forced expression of HOXA1 in human breast cancer cells results in increased cell growth activity. However, it has not been reported in hepatocellular carcinoma (HCC). In this study, we used immunohistochemistry to compare HOXA1 protein expression in HCC and normal liver tissues and further analyzed HOXA1 protein expression in 156 clinicopathologically characterized HCC cases. We stably knocked down the endogenous expression level of HOXA1 in HepG2 cells with specific shRNA-expressing lentiviral vector. Following the successful establishment of stable cells, we examined in vitro cell growth by the MTT assay, anchorage-independent growth through a soft agar colony formation assay and cell migration/invasion by transwell and Boyden chamber assay. In addition, we also investigated in vivo tumor growth by xenograft transplantation of HepG2 cells into nude mice. Our results showed that the protein expression level of HOXA1 was markedly higher in HCC tissues than that in normal liver tissue (P?=?0.019). In addition, a high expression level of HOXA1 protein was positively correlated with the T classification (P?<?0.001), the N classification (P?<?0.001), distant metastasis (P?=?0.004), and the clinical stage (P?<?0.001) of HCC patients. Patients with higher HOXA1 expression showed a significantly shorter overall survival time compared with patients with low HOXA1 expression. Multivariate analysis suggested that HOXA1 expression might be an independent prognostic indicator (P?<?0.001) for the survival of patients with HCC. HOXA1-specific shRNA (shHOXA1) successfully knocked down HOXA1 endogenous expression in HepG2 cells. Compared to the parental and control shRNA-transfected (shCtrl) HepG2 cells, the shHOXA1 cells exhibited significantly reduced in vitro cell growth, anchorage-independent growth, and cell migration and invasion (P?<?0.05). In vivo, the xenograft transplants from shHOXA1 cells gave rise to much smaller tumors compared with those from shCtrl cells. Collectively, high HOXA1 expression is associated with poor overall survival in patients with HCC. The downregulation of HOXA1 inhibits growth, anchorage-independent growth, and migration and invasion of HepG2 cells.     

Hypoxia and retinoic acid-inducible NDRG1 expression is responsible for doxorubicin and retinoic acid resistance in hepatocellular carcinoma cells

Hypoxia may activate survival signals in cancer cells. Moreover, hypoxic cells are less sensitive than normoxic cells to doxorubicin cytotoxicity, a potent activator of the p53 tumor suppressor gene. N-myc downstream-regulated gene-1 (NDRG1) is a hypoxia- and retinoic acid-inducible protein, and has been previously implicated in carcinogenesis. As this protein is also a downstream target of p53 and hepatocellular carcinoma (HCC) cells frequently evidence resistance to retinoic acid (RA) cytotoxicity, we attempted to determine whether the suppression of NDRG1 expression may sensitize HCC cells to doxorubicin and/or RA cytotoxicity. HCC cells expressed NDRG1 protein, and the expression of this protein was hypoxia- and RA-inducible. Doxorubicin treatment induced HCC cell cytotoxicity via the activation of mitochondrial apoptotic signals, including caspase-9 activation. Hypoxic HCC cells are less sensitive to doxorubicin-induced apoptosis. The suppression of NDRG1 expression either by siRNA or flavopiridol sensitized hypoxic HCC cells to doxorubicin cytotoxicity, and this was attributed to more profound augmentation of JNK and caspase-9 activation. The suppression of NDRG1 expression also sensitized RA-resistant HCC cells to RA-induced apoptosis, and this sensitization was more apparent in hypoxic HCC cells than in normoxic cells. Glutaredoxin2 expression was down-regulated in NDRG1-suppressed HCC cells. These results show that hypoxia- and RA-inducible NDRG1 expression is responsible for doxorubicin and RA resistance in HCC cells. Thus, the selective interruption of NDRG1 signaling may prove to be therapeutically useful in HCCs, particularly in the advanced infiltrative type of tumors exposed to hypoxic environments.     

NDRG2基因对结肠癌细胞SW620增殖和侵袭力的影响

目的 观察N-myc下游调节基因2(NDRG2)对结肠癌细胞SW620生长和侵袭能力的影响,并探讨其机制.方法 采用阳离子脂质体转染方法,分别将pcDNA3.1-NDRG2和siRNA-NDRG2转染入SW620细胞内,以空白组作为对照.Western blotting检测各组细胞NDRG2以及基质金属蛋白酶-2(MMP-2)的表达情况;细胞侵袭试验对各组细胞侵袭能力进行分析;四甲基偶氮唑蓝法对各组细胞生长曲线进行测定.结果 pcDNA3.1-NDRG2转染入SW620细胞后,NDRG2蛋白表达升高,而MMP-2蛋白表达降低;siRNA-NDRG2转染入SW620细胞后,NDRG2蛋白表达降低,而MMP-2蛋白表达升高.pcDNA3.1组的穿膜细胞数(56.20±7.40)及siRNA组穿膜细胞数(94.20 ±9.23)分别与对照组(75.80 ±4.82)相比,差异具有统计学意义(t=13.102,P=0.000;t=11.820,P=0.000).生长曲线显示,转染后第5天,pcDNA3.1组细胞吸光度值(0.46 ±0.01)及siRNA组细胞吸光度值(0.91 ±0.02)分别与对照组(0.67 ±0.01)相比,差异具有统计学意义(t=9.561,P=0.000;t=10.922,P=0.000).结论 NDRG2能降低结肠癌细胞SW620的侵袭和增殖能力,其机制可能与下调MMP-2的表达有关.     

High ADAM8 Expression is Associated with Poor Prognosis in Patients with Hepatocellular Carcinoma

In this study,we investigated the ADAM8 expression in hepatocellular carcinoma (HCC) and its correlation with clinicopathologic features,including the survival of patients with HCC. Furthermore,we examined the biological processes regulated by ADAM8 during the development of using HepG2 cell line as a model system. We used immunohistochemistry to compare ADAM8 protein expression in HCC and normal liver tissues and further analyze the ADAM8 protein expression in clinicopathologically characterized 105 HCC cases.We stably knocked down the endogenous expression level of ADAM8 in HepG2 cells with specific shRNA-expressing lentiviral vector. Following the successful establishment of stable cells,we examined in vitro cell growth by MTT assay,anchorage-independent growth by soft-agar colony formation assay and cell migration/invasion by transwell and boyden chamber assay. And in addition,we also investigated the in vivo tumor growth by xenograft transplantation of HepG2 cells into nude mice. Protein expression level of ADAM8 was markedly higher in HCC tissues than that in the normal liver tissues (P?=?0.0058).In addition,high expression of ADAM8 protein was positively correlated with serum AFP elevation,tumor size,histological differentiation,tumor recurrence,tumor metastasis,and tumor stage. Patients with higher ADAM8 expression showed a significantly shorter overall survival time than patients with low ADAM8 expression. Multivariate analysis suggested that ADAM8 expression might be an independent prognostic indicator (p?=?0.016) for the survival of patients with HCC. ADAM8-specific shRNA (shADAM8) successfully knocked down its endogenous expression in HepG2 cells. Compared to the parental and control shRNA-transfected (shCtrl) HepG2 cells,the shADAM8 cells exhibited significantly reduced in vitro cell growth,anchorage-independent growth,cell migration and invasion (p?<?0.05).In vivo,the xenograft transplants from shADAM8 cells gave rise to much smaller tumors as compared to those from shCtrl cells. High ADAM8 expression is associated with poor overall survival in patients with HCC. Down-regulation of ADAM8 inhibits the growth,anchorage-independent growth,migration and invasion of HepG2 cells. ADAM8 may be a potential target of antiangiogenic therapy for HCC.     

A peroxisome proliferator-activated receptor gamma antagonist induces vimentin cleavage and inhibits invasion in high-grade hepatocellular carcinoma

Increased expression of vimentin in carcinomas correlates with parameters of malignant potential such as tumor grade and tumor metastasis. Peroxisome proliferator-activated receptor gamma (PPARgamma) has been intensively evaluated as a potential target for the inhibition of cell growth and metastasis in cancer cells. In the present study, we examined whether PPARgamma is a possible target molecule for the prevention of cell growth and invasion by treatment with agonists (troglitazone, rosiglitazone) and antagonists (T0070907, GW9662) in four different hepatocellular carcinoma (HCC) cell lines. We also evaluated the effects of the PPARgamma agonists and antagonists on tumor cell migration and invasion. The expression level of PPARgamma protein was higher in the sarcomatoid SH-J1 and poorly differentiated HLE cell lines than that in the well-differentiated HCC cell lines (HepG2 and Huh-7). Expression of vimentin was high in the SH-J1 HCC cell line and minimally detected in the HLE cell line. Treatment with low doses of the PPARgamma antagonists inhibited cell growth and colony formation of all four of the HCC cell lines. Vimentin in the high-grade HCC cells was cleaved by the treatment with the PPARgamma antagonists. Furthermore, treatment with the PPARgamma antagonists also strongly inhibited migration and invasion of the SH-J1 and HLE cells. However, treatment with low doses of the agonists had no effect on vimentin expression, migration, and invasion of the high-grade HCC cells but cell growth was inhibited by treatment with high concentrations of the agonists. Our results indicate that treatment with a PPARgamma antagonist may prevent cell growth and invasion of high-grade HCC cells. Our findings also suggest that PPARgamma antagonists inhibit cell growth and invasion through vimentin disarrangement in high-grade HCC.